My old OS is 86x but Installed win10pro 64x?

[Windows Central Question]

how this happen? my pc is so lag now..

if i revert back to old os can i upgrade again to 86x for free?

or i need to buy key now?

 

[xandros9]

that isn't possible, you can't upgrade from 32-bit to 64-bit without starting from scratch.

If you get back to your old OS you'll be able to upgrade again, but how do you know its x64/64-bit? Have you tried a system refresh?